System of electrical distribution.



E. W. STULL.

SYSTEM OF ELECTRICAL DISTRIBUTION.

APPLICATION IILIED JULY 18; 1908.

Patented July 4, 1911.

\w nX ofl I wwm $1.9m 2% 5% MW QAZX UNITED STATES; PATENT OFFICE.

EMMETT W. STULL, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO ALLIS-CHALMERS COMPANY, A CORPORATION OF NEW JERSEY.

SYSTEM OF ELECTRICAL DISTRIBUTION.

' citizen of the United-States, residing at Milwaukee, in the county of Milwaukee and State of \Visconsin, have invented certain new and useful Tmprovei'nents 1n Systems 0t Electrical Distribution, of which the following is a full. clear, and exact specification.

My invention relates to a system of circuits for maintaining constant the voltage of a circuit which is. supplied from a circuit of variable voltage.

A great many electrical devices require a constant voltage supply in order to operate satisfactorily. This is especially true of inca ndcscent lamps, the light from which varies much more rapidly than the voltage of the lamp circuit. lint often incandescent lamps are supplied from circuits having a variable voltage, such for instance as when they are connected to power circuits in shunt to motors, as on the ordinary electric cars, or are supplied by variable speed generators, as by n'ei'icrators driven by car axles. In order to prevent fluctuations in the light, it is necessary in such cases to provide auxiliary means to maintain constant the voltage supplied to the lamps.

t is the object of my present invention to do this.

My invention may be briefly described as comprising a variable voltage circuit, a second circuit supplied therefrom, a generator armature through which the second circuit is supplied from the variable voltage circuit, and means for so varying and reversing the voltage of the generator that the algebraic sum of the voltages of the variable voltage circuit and of the generator is substantially constant. This variation of the generator voltage is preferably obtained by connecting its field winding in the bridge wire of a sort of \Vheatstone bridge arrangement connected across the variable voltage circuit, one pair of opposite arms of the bridge consisting of ohmic resistances while the other pair of opposite arms comprises ,batteries or other counter electrometive force devices.

The particular novel features of my in-' Specification of Letters Patent.

Application filed July 18, 1908.

Patented July 4, 1911. Serial No. 444,288.

The single figure of the drawings shows my invention as applied to the lighting circuit on an ordinary electric railway car.

The main car circuit ;\B is connected between the trolley 10 and the ground. The motor circuit ll 12 is connected across the circuit i\li. The arrangement and control of the motors in the motor circuit is immaterial so far as my present invention concerned. The lamps 13 are connected across a circuit H15 which is supplied from the circuit AB in shunt to the motor circuit 11-42. But since the circuit AB is essentially a power circuit, and since varying amounts of power will be required elsewhere from the same main supply circuit, the lamps 13 are connected to the circuit i\--B through the armature 16 of a generator, the voltage of this generator being so regulated, as hereinafter described, that the voltage of the circuit l t-l5 is substantiallfv constant. This generator is driven by a motor 17, preferably shunt-wound, this motor being connected across the constantvoltage circuit 1-l -l5 in order to have a substantially constant speed. Also connected across the circuit \B is a device for regulating the voltage of the generator 16. This device. consists of a sort of W'heatstone bridge ll. one pair of opposite arms of the bridge containing storage batteries 18 and 19 respectively, or other counter electromotive force devices, and the other pair containing adjustable ohmic resistances Q0 and 21 respectively. The field winding 2:2 of the generator 16 is connected in the bridge wire of this \Vheatstone bridge, or between the points 232 In order that the batteries 18 and 19 need not be too large, a resistance 25 is preferably connected in the circuit containing the bridge.

The operation of the arrangement is as follo\vs:lVhen the voltage of the main supply circuit, or of the circuit A-B, which corresponds in voltage to the main supply circuit, is at a predetermined value, this value being determined by the voltage that should be impressed on the circuit l415 and on the lamps 13, the drops in Voltage in the batteries 18 and 1 9 are equal respectively to the drops in voltage in the resistances 20 and 21. Consequently the points'23 and 24: are at the same potential, and no current flows in the winding 22. The generatorarmature 16, though driven as usual at a constant speed by the motor 17, generates no electroanotive force, and the voltage of the "'i'shed.

"quently the potential of the point 2& rises relatively to that of the point 23, the trolley being assumed to be on the positive side of the generator armature 16 to generate an the circuit, and current flows downward through the field winding 22, thus causing electromotive force which is added to the electromotive force of the main circuit and impressed on the circuit 1415. The greater the fall in the voltage of the main circuit below the aforesaid predetermined value, the greater the current is in the field winding 22, and consequently the voltage supplied by the generator 16 to assist the voltage of the main circuit increases as the latter voltage decreases. Similarly, as the voltage in the main circuit increases above the aforesaid predetermined value, the current through the device R increases and the drops in'the resistances 20 and 21 increase. But, as before, the drops in the batteries 18 and 19 remain substantially unchanged. Consequently the potential of the point 28 rises above that of the point 24:, and current flows upward through the field winding 22. This causes the generator armature 16 to generate an electromotive force which opposes the electromotive force of the main circuit, and which varies with the increase of said latter electromotive force above the aforesaid predetermined value.

By properly proportioning the various parts, the generator armature 16 may be made to generate an electromotive force of such value that the algebraic sum of the electromotive forces of the main circuit and of the generator armature 16 is a constant, equal to the constant voltage required by the circuit 115. By varying the resistances- 20 and 21, similarly or dissimilarly, as required, the predetermined voltage referred toabove may be made anything desired. This predetermined voltage maybe equal to, above, or below, the normal voltage of the main supply circuit. ,In order to prevent a discharge of the batteries 18 and in case the trolley 10 leaves the trolley wre or a no voltage condition arises for any other reason, a double pole switch 26 is provided with one-pole in the connection between the main circuit and the. regulating device It and the other in the bridge wire of such device. This switch is biased to open position, but is moved to closed position by a solenoid 27 when the main supply circuit is alive and the car cir-. cuits are connected thereto. Switches 28 and 29 may be provided, so that the lights 13, the motor generator set 1617, and the regulating device B may be disconnected from the circuit.

In the arrangement described above they batteries 18 and 19 are arranged merely for regulating purposes. But if the resistance 25 is omitted and the batteries 18 and 19 are made of sufiicient capacity, the system is equally applicable to cases where the fluctuations in the supplied voltage vary much more widely, as in the case of axle-driven generators. In such cases, the batteries 18 and 19 can supply current to the lamps 13 for a limited time, even when the main source is entirely out of service.

Many modifications may be made in the precise arrangements herein shown and described, and all such which do not involve a departure from the spirit and scope of my invention I aim to cover in the following claims.

l/Vhat I claim as new is:

1. In combination, a circuit of variable voltage, a second circuit supplied therefrom, a generator in the connection between the two circuits, and a vVheatstone bridge connected across the circuit of variable voltage and having arms in opposite ones of \which the drops in voltage vary proportionately and in adjacent ones of which the drops in voltage vary disproportionately as the voltage of the variable voltage circuit varies, the field winding of said generator being connected in the bridge wire of said Wheatstone 'bridge.

2. In combination, a circuit of variable voltage, a second circuit supplied therefrom, a generator in the connection between the two circuits, and a Wheatston'e bridge connected across the circuit of-variable voltage and having arms in any. two adjacent .ones of which the drops in voltage vary dissimilarly as the voltage of the variable voltage circuit varies, the field winding of said generator being connected in the bridge wire of said W'heatst0ne bridge.

3. In combination, a circuit of variable voltage, a second circuit supplied therefrom, a generator in the connection between the two circuits, a regulating device connected across the circuit of variable voltage and comprising a VVheatstone bridge having similar counter electromotive force devices in two opposite arms, the field winding of the generator being connected in the bridge voltage, a second circuit supplied therefrom, a generator armature in the connection between the two circuits, a regulating device connected across the circuit of variable voltage and comprising an electric balance, the voltage drops in any two adjacent arms of which vary disproportionately, and a field winding for said generator armature connected in the bridge wire of said balance.

5. In combination, a circuit of variable voltage, a second circuit supplied therefrom, a generatorarmature inthe connection between the two circuits, a field winding co operating with said armature, and a regulating device for said field winding, said regulating device comprising a \Vhcatstone bridge connected across the circuit of variable voltage and having counter electromotive force devices in two of its opposite arms and ohmic resistances in the other two opposite arms, said field winding being connected in the bridge wire of said heatstone bridge.

6. A regulator for dynamo-electric machines comprising a W'heatstone bridge, counter electromotive force devices in two opposite arms of said bridge, ohmic resistances in the other two opposite arms thereof, and a controlling magnet'winding in the bridge wire thereof.

7. In combination, a circuit of variable voltage, a second circuit supplied therefrom, a generator in the connection between the two circuits, and a \Vheatstone bridge connected across the circuit of variable voltage and having arms in any two opposite ones of which the drops in voltage vary proportionately as the voltage of the variable voltage circuit varies, the field winding of said five cents each, by addressing the Commissioner of Washington, I). C.

generator being connected in the bridge wire of said \Vheatstone bridge.

8. In combination, a circuit of variable voltage, a second circuit supplied therefrom, a generator armature in the connection be tween thetwo circuits, a regulating device connected across the circuit of variable volt age and comprising an electric balance, the voltage drops in any two opposite arms of which vary proportionately and in adjacent arms of which vary disproportionately as the voltage of the variable voltage circuit varies, and a field winding for said generator armature connected in the bridge wire of said balance.

9. In combination, a circuit of variable voltage, a second circuit supplied therefrom, a generator in the connection between the two circuits, and a \Vheatstone bridge connected across the circuit of variable voltage and having storage batteries connected in one pair of opposite arms and ohmic resistances in the other pair of opposite arms, the field winding of said generator being connected in the bridge wire of said \Vheatstone bridge. 7

10. A regulator for a dynamo-electric machine comprising a \Vheatstonc bridge, storage batteries connected in two opposite arms of said bridge, ohmic resistances connected in two opposite arms thereof, and a control-. ling magnet winding in the bridge w re thereof.

In testimony whereof I afiix my signature, in the presence of two witnesses.

4 EMMETT \V. STULL.

- Witnesses H. C. CASE, Fnnb J. KINsEv Patents, 

